1. Field of the Invention
This invention relates to a ruthenium complex, more particularly to a ruthenium complex for a dye-sensitized solar cell.
2. Description of the Related Art
Photovoltaic cells, sometimes called solar cells, are being increasingly developed in the art due to the fact that sunlight to be converted into electrical energy via the photovoltaic cells is inexhaustible. A dye-sensitized solar cell (DSSC) is one of the photovoltaic cells having most potential. The dye contained in the DSSC is used to absorb visible and near infrared light from the sun to excite electrons. The excited electrons are then injected into a conduction band of a semiconductor electrode so as to produce photocurrent. Therefore, the photovoltaic conversion efficiency of the DSSC is affected primarily by the performance of the dye. Ruthenium complex is primarily searched and developed as a dye commonly used in the dye-sensitized solar cell.
US 2010/0258175A1 discloses a photosensitizer complex represented by formula (a):MXYZ  (a)where
M represents ruthenium,
X represents a monodentate anion ligand selected from halide, pseudohalide, carboxylate, carbanion, sulfate, phosphate, thiocyanate, and other organic anion,
Y represents a heterocyclic bidentate ligand including a structural formula represented by Formula (b) or Formula (c) listed below:
where
G1 comprises a structural formula represented by Formula (d), Formula (e), Formula (f), or Formula (g) listed below:

G2 comprises a structural formula represented by Formula (h), Formula (I), or Formula (j) listed below:

Z represents a tridentate ligand including a structural formula represented by Formula (k) listed below:
where
Ra, Rb, Rc, Rd, Re, Rf, Rg, Rh, Ri, and Rj are the same or different, and represent a C1-C8 alkyl group, a C1-C8 alkoxyl group, a C1-C8 alkylthio group, a C1-C8 alkylamino group, a C1-C8 halogenated alkyl group, a phenyl group or a substituted phenyl group containing C1-C6 alkyl or alkoxyl group, a triphenylamino group or a substituted triphenylamino group containing a C1-C6 alkyl or alkoxyl group, a carboxylic acid group or a carboxylate group, a sulfonic acid group or a sulfonate group, a phosphoric acid group or a phosphate group, an amino group, halogen, or hydrogen; or
Rc and Rd comprise a structural formula represented by Formula (m) listed below:

A photosensitizer complex disclosed in US 2010/0258175A1 is represented by the following Formula (n):
whereRk represents hydrogen, OCH3, OC8H17, or an isobutyl group. When the photosensitizer complex of Formula (n) is utilized in the dye-sensitized solar cell, the dye-sensitized solar cell has an open circuit voltage ranging from 668 V to 720 V, a short circuit current density ranging from 20.3 mAcm−2 to 21.7 mAcm−2, and a photovoltaic conversion efficiency ranging from 9.14% to 10.05%. However, the demand for the photovoltaic conversion efficiency of the dye-sensitized solar cell is always increasing, and the photosensitizer complex disclosed in US 2010/0258175A1 may not meet current industrial requirements.